I just read the first thread you linked to, so to quote myself:
"I post a lot on FT & I don't want to get a gazillion emails/notifications if someone has quoted me."
MarriottInsiders (Marriott's version of FT on its own website) has that function & it drives me crazy when I get a lot of emails saying someone has mentioned/quoted me/clogs up my inbox. I also don't need a bunch of pop-ups telling me the same thing.
Cheers.